Low hydrocarbon emission fuel tank with internal components

ABSTRACT

A low permeation fuel tank formed with a first half and a second half includes a hydrocarbon barrier and a fuel system module. The hydrocarbon barrier reduces the emission of hydrocarbons from the fuel tank. Minimization of discontinuities in the hydrocarbon barrier is achieved by positioning the fuel system module within the fuel tank. The fuel system module includes a preformed sheet to provide flexible and rigid support to the fuel tank. In addition, the fuel system module may include fuel system components, structural enhancements of the fuel tank and/or functional features of the fuel tank to minimize production of holes or other discontinuities in the hydrocarbon barrier.

[0001] This application claims the benefit under 35 U.S.C. §119(e) ofProvisional U.S. patent application Ser. No. 60/224,487 filed on Aug.11, 2000.

BACKGROUND

[0002] 1. Field of the Invention

[0003] This invention relates to fuel tanks, and more particularly to alow permeation fuel tank that includes internally mounted components.

[0004] 2. Description of the Related Art

[0005] Fuel tanks made of plastic or metal are well known for providinga reservoir of fuel for engines and other fuel consuming devices inland, water and air vehicles. A hydrocarbon barrier is typicallyincluded in fuel tanks to prevent passage of fuel and associated vaporstherethrough. Additional components are usually added to the fuel tankto create a fuel system. The components may include valves, hoses,pumps, level sensors, structural supports, etc. Typically, some of thesecomponents are installed inside the fuel tank by cutting service holesin the tank. In addition, some of the components are installed outsidethe tank requiring additional holes, grooves and/or recesses.

[0006] Recent changes in government regulations have reduced the amountof allowable fuel vapor emissions from fuel tanks. One way to reduceallowable fuel vapor emissions is through minimization of breaches inthe hydrocarbon barrier. Reduction in the number of holes in the fueltank through internalization of fuel system components minimizesbreaches. One way to internalize fuel system components is to insert thecomponents during manufacture of the tank.

[0007] Some fuel tanks are manufactured with a structure inside thetank. The structure provides for internalized mounting of fuel systemcomponents. In addition, the structure includes rigid columns that arerigidly connected with opposite walls of the fuel tank to maintain thestructure in position. The columns are located to generally define theperimeter of the structure. In addition to supporting the remainingstructure, the columns also provide local structural support for thefuel tank. The remaining structure is created with rigid members. Someof the rigid members include compliant joints to allow the otherwiserigid structure to distort in response to external forces. Such astructure is described in U.S. Pat. No. 6,138,859 to Aulph et al.

[0008] One problem with prior art structures is the significant cost andcomplexity that is added to the tank to achieve structural support andthe ability to distort in the presence of external forces. Manufacturingfuel tanks with prior art structures involves forming each of theindividual members/columns, coupling the members and columns in apredetermined pattern and then coupling the resulting structure with afuel tank. The quantity and placement of the members may varysignificantly among different structures depending on the design of thefuel tank. In addition, coupling the columns with opposite walls of thefuel tank may be difficult to perform and/or verify. Aside from thesignificant design and manufacturing requirements to create and installthe structure, accommodation of the structure may adversely affect theoverall design and functionality of the fuel tank.

[0009] For example, the use of columns to support the structure mayrequire placement of columns where no structural support of the fueltank is needed. In addition, columns may provide stiffness that hindersdesirable crushing and/or folding characteristics of the fuel tankduring an impact, such as in a crash situation. Further, shearing andmoment forces applied to only a portion of the tank, such as, forexample, in a crash situation, may be transferred to another portion ofthe tank by the rigid nature of the columns causing additional damage.Finally, column placement required to support the structure mayinterfere with ribbing and other desirable features formed in the wallsof the fuel tank.

BRIEF SUMMARY

[0010] The present invention is defined by the following claims, andnothing in this section should be taken as a limitation on those claims.By way of introduction, the embodiments herein described disclose a fueltank system that includes a fuel system module. The fuel system moduleprovides both rigid and flexible structural support using a fairlyuncomplicated and economical design. The design is relatively easy tomanufacture and install in the fuel tank system. The fuel system modulemay be formed to comply with the shape and structural features presentin the fuel tank system. In addition, the fuel system module may beformed to selectively include formations that provide structural supportand provisions for positioning fuel system components. Further,functional features of the fuel tank system and provisions for mountingthe fuel system module within the fuel tank system may also be included.

[0011] The fuel tank system forms a container that includes a first halfand a second half. The first and second halves are coupled by a weldjoint to form a chamber. The fuel system module is positioned within thechamber prior to coupling the first and second halves to minimize holesand other discontinuities in a hydrocarbon barrier. The hydrocarbonbarrier is formed by the first and second halves, and surrounds the fuelsystem module.

[0012] The fuel system module includes a pre-formed sheet. Thepre-formed sheet is a continuous sheet formed in a predetermined shape.The preformed sheet may include formations to position at least one fuelsystem component thereon. In addition, the pre-formed sheet may beformed to include functional features of the fuel tank system, such as,for example, reservoirs and fuel channeling. The pre-formed sheet mayalso include formations to mount the fuel system module in one of thefirst half and the second half. Mounting of the fuel system module mayinvolve coupling the fuel system module to an interior surface of eitherthe first half or the second half of the container.

[0013] The fuel system module utilizes the pre-formed sheet to provideboth rigid and flexible structural support when subject to forcesexternal and/or internal to the fuel tank system. The pre-formed sheetincludes formations that exhibit rigidity when subject to forcessubstantially perpendicular to the surface of the pre-formed sheet. Inaddition, the pre-formed sheet includes formations that exhibitflexibility when subject to forces substantially parallel with thesurface of the pre-formed sheet. Accordingly, the fuel system module maybe selectively formed to provide resistance to some forces andabsorption of other forces occurring within the fuel tank system.

[0014] An interesting feature of the fuel system module is the absenceof individually manufactured and assembled components and parts toachieve the functionality provided by the pre-formed sheet. Thepre-formed sheet may also be formed contiguous with the contour ofinterior surfaces of the first and second halves. In addition, thepre-formed sheet consumes very little tank capacity while providingsignificant structural and operation functionality. Further, due to theinherent adaptability in the formation of the pre-formed sheet,accommodation of different shapes, structural support requirements andmounting requirements within the fuel system module are relativelysimple.

[0015] Another interesting feature of the fuel system module is theflexible and rigid structural support that may be designed to enhancethe manufacturing process. For example, structural rigidity may beincluded that allows an installation device, such as a robot arm tograsp, manipulate and insert the fuel system module into the fuel tanksystem without damage. In addition, damage to the hydrocarbon barrierwhen the fuel system module is pressed against the interior surface ofthe first or second halves with too much force may be avoided byproviding selective flexibility.

[0016] Yet another interesting feature of the fuel system module is theability to create a single module in which fuel system components may bepre-configured and tested prior to installation in the fuel tank system.As such, cooperative operation of multiple components may be confirmedbefore the fuel system module is sealed within the container.

[0017] Further aspects and advantages of the invention are discussedbelow in conjunction with the preferred embodiments.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

[0018]FIG. 1 is a perspective exploded view of an embodiment of a fueltank system illustrating an embodiment of a fuel system module.

[0019]FIG. 2 is a top view of the fuel system module illustrated in FIG.1.

[0020]FIG. 3 is a cross-section side view of another embodiment of thefuel tank system illustrating another embodiment of the fuel systemmodule.

[0021]FIG. 4 is a perspective view of another embodiment of the fueltank system with a portion cutaway to illustrate another embodiment ofthe fuel system module.

[0022]FIG. 5 is a top view of the fuel system module illustrated in FIG.4.

[0023]FIG. 6 is a perspective view of another embodiment of the fueltank system with a portion cutaway to illustrate another embodiment ofthe fuel system module.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Embodiments of a fuel system module for use in a fuel tank systemare disclosed. The fuel system module comprises at least one pre-formedsheet that is shaped for insertion as a layer between the two halves ofa fuel tank during the manufacturing process. Fuel system components andfunctional features of the fuel system may be included as part of thefuel system module. The fuel system module is formed to providestructural rigidity for supporting the fuel system components andfunctional features while also providing flexibility to alleviateundesirable stresses that may develop. In addition, the fuel systemmodule may be pre-formed in any shape compatible with the structuralfeatures and/or contours of the fuel tank. Support of the fuel systemmodule within one of the two halves of the fuel tank is provided byformations in the pre-formed sheet. The pre-formed sheet also maximizesfuel capacity to within the fuel tank and provides desirable crushingand folding characteristic during an impact.

[0025]FIG. 1 illustrates an exploded perspective view of a fuel tanksystem 10. The fuel tank system 10 forms a container that includes afirst half 12, a second half 14 and a fuel system module 16. In theillustrated embodiment, the fuel tank system 10 is formed as a saddletype fuel tank. In other embodiments, the fuel tank system 10 may beformed in any other shape forming a fuel tank.

[0026] The first half 12 forms the top half and the second half 14 formsthe bottom half of the fuel tank in the illustrated embodiment. In otherembodiments, the first and second halves may be left and right sidehalves, front and backside halves or any other formation of two halvesforming a fuel tank. In still other embodiments, the two halves 12, 14may each be formed of a number of panels connectively coupled to formthe two halves 12, 14. In yet other embodiments, the first and secondhalves 12, 14 may not be two “halves” of the container. For example, thesecond half 12 may form the bottom and sides of the container and thesecond half 14 may form a top cover.

[0027] The first and second halves 12, 14 may be formed of, for example,thermoplastic materials, thermoset materials, metal materials, polymerscontaining both thermoplastic and thermoset materials and/or any othermaterials capable of forming a container that includes a hydrocarbonbarrier. Exemplary thermoset materials include epoxy, phenolic resin(“bakelite”), carbon fiber/epoxy and other thermoset type materials.Metal materials may be, for example, stainless steel or any other metalsthat do not corrode, form gels, or in any other way structurally degradeor degrade the quality of fuel stored therein. Thermoplastic materialsmay be single, or multi-layer, resin based thermoplastic materials.

[0028] In one embodiment, the thermoplastic materials are in the form ofthermoplastic sheets with six layers. The first layer is an outer layerthat includes high-density polyethylene (HDPE) and carbon black. Thesecond layer is an inner layer positioned adjacent to the first layerand includes reground thermoplastic sheet material. A third layerpositioned adjacent the second layer is also an inner layer and includesadhesive polymer. Positioned adjacent the third layer is a fourth layerthat includes ethylene vinyl alcohol (EVOH). The EVOH layer of thisembodiment provides a hydrocarbon barrier for reduction of the emissionof hydrocarbons permeating through the thermoplastic sheet. A fifthlayer is positioned adjacent the fourth layer and includes adhesivepolymer. The sixth layer forms the other outer layer adjacent to thefifth layer and includes HDPE. In other embodiments, differentcompositions, arrangements and quantities of layers may be used to formthe thermoplastic sheet.

[0029] The first and second halves 12, 14 may be formed by stamping,casting, molding or any other technique for forming the desired contour,structural and functional features. The formation technique utilized isdependent to some extent on the materials from which the first andsecond halves 12, 14 are formed. For example, metal materials aretypically stamped, thermoset materials are typically cured in a mold,and thermoplastic materials may be blow molded or thermoformed usingmolds.

[0030] In one embodiment, where thermoplastic sheets are used, the firstand second halves 12, 14 may be formed by twinsheet thermoforming. Anexemplary twinsheet thermoforming technique is disclosed in a co-pendingpatent application entitled “HIGH VOLUME PRODUCTION OF LOW PERMEATIONPLASTIC FUEL TANKS USING PARALLEL OFFSET TWINSHEET PRESSURE FORMING”Ser. No. ______ filed the same day as the present application, which isherein incorporated by reference in its entirety. In general, twinsheetthermoforming allows the first and second halves 12, 14 to be formedseparately from molten thermoplastic sheets. The thermoplastic sheetsare formed into the first and second halves 12, 14 and brought togetherunder controlled conditions to be hermetically sealed to form thecontainer.

[0031] In the illustrated embodiment, the first half 12 includes acontoured top surface 20 that laterally extends to a contoured sidesurface 22. The side surface 22 surrounds and extends variouspredetermined distances generally perpendicular to the top surface 20 toan edge 24. The edge 24 generally forms a lip or a flange compatiblewith the second half 14. The top surface 20 and the side surface 22 forma generally concaved shape with a first interior surface 26.

[0032] The first half 12 of this embodiment also includes at least oneaccess port 28 and a fill neck 30. The access port 28 is a formationwithin the contoured top surface 20. The access port 28 includesprovisions for creating an aperture to access the interior of the firstand second halves 12, 14 following sealing. In addition, the access port28 may also be formed to couple a cap 32 to the first half 12 by, forexample, snap fit, threaded connection, snap lock or some other couplingmechanism. In other embodiments, the access port 28 and cap 32 is notincluded. The fill neck 30 is formed in the side surface 22 to providean entrance into the container for fluids, such as, for example, fuel.In other embodiments, the fill neck 30 may be formed in the top surface20 or the second half 14.

[0033] The second half 14 similarly includes a contoured top surface 34laterally extending to a contoured side surface 36. The side surface 36extends a predetermined distance generally perpendicular to the topsurface 34 to an edge 38. The edge 38 is formed to create a seal withthe edge 24 of the first half 12 when the first and second halves 12, 14are brought together. The top surface 34 and the side surface 36generally form another concaved shape with a second interior surface 40.When the first and second halves 12, 14 are brought together the edges24, 38 are sealed by formation of a weld joint. The weld joint, orpinchoff, is positioned to surround the periphery of the first andsecond halves 12, 14 and form a hermetic seal.

[0034] Once sealed, the first and second interior surfaces 26, 40 definea chamber in which fluids, such as, for example fuel may be stored. Eachof the first and second halves 12, 14 also include a continuoushydrocarbon barrier surrounding the chamber to deter migration of fluidout of the chamber. In one embodiment, the first and second halves 12,14 form a low permeation plastic fuel tank.

[0035] The fuel system module 16 is positioned within the chamberdefined by the first and second halves 12, 14. The fuel system module 16provides a single module encompassing whatever functionality is selectedfor inclusion within the fuel tank system 10. Accordingly, the selectedfunctionality may be relatively quickly and easily installed duringmanufacture of the fuel tank system 10.

[0036] In addition, the fuel system module 16 may comprise functionalityrequiring cooperative operation of a number of different components. Bybuilding the functionality as part of the fuel system module 16,cooperative operation of the components may be verified. Verificationmay be performed prior to installation of the fuel system module 16.Further, a low hydrocarbon emission fuel tank may be created since thefuel system module 16 is completely enclosed within the hydrocarbonbarrier provided by the first and second halves 12, 14.

[0037] The embodiment of the fuel system module 16 illustrated in FIG. 1includes at least one fuel system component 44 and a pre-formed sheet46. The fuel system component 44 may be a valve, a hose, an electricconductor, a pump, a filter, a sensor or any other fuel system relatedmechanism and/or feature. In the illustrated embodiment, a plurality offuel system components 44 are depicted. Namely, FIG. 1 includes a fuellevel vent valve (FLW) 44 a, a rollover valve 44 b, and a plurality ofhoses 44 c for transporting fuel and vapors. In other embodiments,additional or fewer fuel system components 44 may be included. The fuelsystem components 44 are positioned contiguous with the pre-formed sheet46.

[0038] The pre-formed sheet 46 may be any sheet fashioned in apredetermined shape forming a continuous layer between the first andsecond halves 12, 14. As used herein, the term “sheet” refers tomaterials with opposing surfaces in which the thickness of the materialsbetween the opposing surfaces are thin in comparison to the lengthand/or the width of the opposing surfaces. The pre-formed sheet 46 maybe relatively flat or may include contours, ridges, ribs, flanges, fins,folds, cavities, grooves, notches, troughs, passageways, holes or anyother formations formable within a sheet. The pre-formed sheet 46 may beformed from polymers such as for example, thermoplastic material,thermoset material or a combination of both. In addition the pre-formedsheet 46 may be formed of metal or any other semi-rigid material capableof being fashioned into a sheet with a predetermined functional shape.

[0039] In the presently preferred embodiments, the pre-formed sheet 46provides both a rigid structure and a flexible structure as a functionof the shape of the pre-formed sheet 46. A sheet is inherentlyrelatively stiff when subject to forces acting in directionssubstantially perpendicular to the opposing surfaces, and relativelyflexible when subject to forces acting in directions substantiallyparallel to the opposing surfaces.

[0040] As used herein, “substantially parallel” refers to forces with alarger shear stress component and a smaller normal stress componentacting on the opposing surfaces of the sheet. Similarly, “substantiallyperpendicular” refers to those forces with a larger normal stresscomponent and a smaller shear stress component acting on the opposingsurfaces of the sheet. In addition, references herein to “surfaces” ofthe pre-formed sheet 46 refer to the orientation of the plane generallyoccupied by the extending pre-formed sheet 46 and not the individualformations thereon.

[0041] By strategically shaping formations within the pre-formed sheet46, rigidity when exposed to some forces, and flexibility when exposedto other forces may be achieved. The formations may also be designed andshaped with pre-determined failure levels to provide predictablecrushing and folding characteristics when subject to excessive and/orundesirable forces. Forces the pre-formed sheet 46 may be subject toinclude external forces imparted on the fuel tank system 10 as well asinternally created forces. Exemplary external forces include vibration,impact forces and vacuum/pressure created in the fuel tank system 10. Onthe other hand, exemplary internal forces include shrinkage and swellingbetween structures, transient thermal imbalances due to uneven heatingand cooling and dynamic loading caused by lateral movement of the fuelsystem components 44 or fuel within the fuel tank system 10.

[0042] For example, the pre-formed sheet 46 may include formations thatallow the application of pressure to urge the fuel system module 16 intocontact with the first interior surface 26 or the second interiorsurface 40. Rigidity designed into the pre-formed sheet 46 allowsmanipulation by, for example, a robot arm without creating undesirableand potentially damaging deformation and/or stress of the fuel systemmodule 16. Design of the preformed sheet 46 may also include flexibilityto alleviate any excessive pressure that may otherwise cause damagingstress to the hydrocarbon barrier when the fuel system module 16 isurged into contact. Accordingly, the fuel system module 16 absorbsundesirable stresses while at the same time providing rigid resistanceto other stresses to maintain the integrity and functionality of thefuel tank system 10.

[0043] In one embodiment, the pre-formed sheet 46 is formed fromthermoplastic material. The thermoplastic material may be formed by blowmolding, thermosetting, and/or any other technique for formingthermoplastic. In one embodiment, the thermoplastic material is a singlecontinuous thermoplastic sheet. In other embodiments, the thermoplasticmaterial may include at least two separately formed thermoplastic sheetsthat are welded, or otherwise coupled together to form a continuoussheet.

[0044] The pre-formed sheet 46 may also include at least one functionalfeature 48 formed within the pre-formed sheet 46. Exemplary functionalfeatures 48 include a liquid reservoir, a liquid channel, a baffle,provisions for fuel system components 44, provisions for coupling thepre-formed sheet 46 to one of the first and second halves 12, 14, astructural support and/or any other functional features pertaining tofuel systems and fuel system operation. The pre-formed sheet 46 may alsoinclude apertures. The apertures may be located to allow the flow offuel and air through the pre-formed sheet 46, as well as avoidingundesirable pooling of fuel and creation of air pockets.

[0045] In addition, the functional features 48 within the pre-formedsheet 46 may include formations to provide stiffness as well asflexibility when subject to internal and external forces. For example,through selective formation of the functional features 48, forcesapplied substantially perpendicular to surfaces of the pre-formed sheet46 may be presented with stiffness. Similarly, forces appliedsubstantially parallel with surfaces of the pre-formed sheet 46 may bepresented with flexibility. In addition, functional features 48 may beformed to allow the pre-formed sheet 46 to selectively react withflexibility and/or stiffness to non-parallel and/or non-perpendicularshearing forces, as well as moment loading, within the fuel tank system10.

[0046] In the illustrated embodiment, the functional features 48 includea first feature 48 a, a second feature 48 b and a third feature 48 c.The first feature 48 a includes a number of functional characteristics.One characteristic is structural and is provided by a cylindrical,hollow, generally barrel shaped first housing 50 formed in the preformedsheet 46. In other embodiments, the formation forming the first housing50 may be generally shaped as, for example, square, rectangular,spherical, conical, elliptical or any other shape.

[0047] The first housing 50 may longitudinally extend to beperpendicular and adjacent to both the first interior surface 26 and thesecond interior surface 40 when the first and second halves 12, 14 arebrought together. The nature of the formation of the first housing 50allows the pre-formed sheet 46 to provide rigid support when the firstand second halves 12, 14 are subject to compressive forces. Exemplarycompressive forces include forces induced by vacuum, bending and warpingthat may cause the first and second halves 12, 14 to move closertogether. It should be noted that the first housing 50 does not providea fixed rigid connection between the first and second surfaces 26, 40.In addition, the first housing 50 may be formed to be adjacent only thefirst or the second halves 12, 14 and provide no rigid support.

[0048] Another characteristic provided by the first housing 50 issupport for fuel system components 44 inserted into the hollow withinthe first housing 50. The support may be formed to be rigid and/orflexible. For example, the preformed sheet 46 may flex to allow the fuelsystem component 44 to move substantially parallel to surfaces of thepre-formed sheet 46 while remaining rigid against movement perpendicularto surfaces of the pre-formed sheet 46.

[0049] In the illustrated embodiment, a fuel system component 44, suchas, for example, a fuel pump may be positioned within the first housing50. Installation of the fuel system component 44 may be performed byremoving the cap 32 and lowering the fuel system component 44 throughthe access port 28. Alternatively, the fuel system component 44 may beinstalled before the first and second halves 12, 14 are sealed together.The fuel system component 44 may be held within the first housing 50 byfriction fit, screw connection, snap-fit, welding, gluing or any othermechanism for coupling the fuel system component 44 to the first housing50.

[0050]FIG. 2 illustrates a top view of a portion of the fuel systemmodule 16 with the fuel system components 44 removed and portions of thepre-formed sheet 46 cross-sectioned. Another characteristic provided bythe illustrated embodiment of the first feature 48 a is a reservoirformed by the hollow within the first housing 50 that includes a swirlpot 52. The swirl pot 52 is formed in the pre-formed sheet 46 to providea channel for flow of liquid through an aperture 54 in the first housing50. The swirl pot 52 operates in a well-known manner to retain fuelwithin the first housing 50.

[0051] Referring now to FIGS. 1 and 2, the second feature 48 b of thisembodiment similarly includes a cylindrical, hollow, generally barrelshaped second housing 56 formed in the pre-formed sheet 46. The secondhousing 56 similarly includes provision to accept at least one fuelsystem component 44 such as for example, the FLW 44 a and/or the rollover valve 44 b. In addition, the second housing 56 may provide rigidityand/or flexibility within the pre-formed sheet 46 similar to the firsthousing 50. In other embodiments, the formation of the second feature 48b may be generally shaped as, for example, square, rectangular,spherical, conical, elliptical or any other shape.

[0052] In another embodiment, the first and second housings 50, 56 maybe used as temporary positioning devices for the fuel system components44. During manufacture, a fuel system component 44 may be temporarilypositioned in one of the first or second housings 50 or 56. The fuelsystem component 44 is maintained in a predetermined position andcoupled to the first or second interior surfaces 26 or 40. In otherembodiments, the fuel system components 44 may be temporarily positionedby other formations within the pre-formed sheet 46.

[0053] Coupling occurs when the first and second halves 12, 14 arebrought together and the fuel system component 44 is pressed against thefirst or second interior surfaces 26 or 40 by the first or secondhousings 50 or 56. In one embodiment, the first and second housings 50,56 may be formed in the pre-formed sheet 46 to provide sufficientflexibility and rigidity (compressive resistance) to promote propercoupling of the fuel system component 44. Sufficient flexibility may,for example, prevent the fuel system component 44 from being embedded toan undesirable depth in the first or second interior surfaces 26 or 40.

[0054] The third feature 48 c of the illustrated embodiment comprises aplurality of ribs, or channels selectively formed in the pre-formedsheet 46 for enhancement of the structural integrity of the fuel systemmodule 16. The ribs may be selectively formed to enhance flexibility aswell as rigidity. Other features may also be formed in the preformedsheet 16, such as, for example, apertures to provide a baffling functionfor slosh abatement and noise control as well as improved durability.Other exemplary formations such as, shelves, grooves, notches or foldsprovided to maintain the position of the hoses 44 c or any otherfunctional features 48 may be formed in the pre-formed sheet 46. Inaddition, the pre-formed sheet 46 as a whole may serve as a condensingsurface and an anti-turbulence system to reduce fuel-air mixing andresultant fuel vapor generation.

[0055] The fuel system module 16 may be positioned in either the firsthalf 12 or the second half 14 during the manufacturing process. In oneembodiment, the fuel system module 16 is fixedly coupled to either thefirst interior surface 26 or the second interior surface 40. In thisembodiment, the pre-formed sheet 46 may include formations to providerigid and/or flexible coupling. The formations for coupling maycooperatively operate with other formations in the pre-formed sheet 46similarly providing rigidity and or flexibility. Exemplary formationsfor coupling may include areas of the pre-formed sheet 46 formed to becontiguous with the first interior surface 26 or the second interiorsurface 40.

[0056] The formations may be fixedly coupled with the contiguous firstor second interior surface 26 or 40 by, for example, welding, gluing orany other coupling mechanism that does not compromise the hydrocarbonbarrier. In another embodiment, some form of adapter mechanism may beformed from the pre-formed sheet 46 or provided as a separate device tofacilitate coupling. An exemplary adapter mechanism is disclosed in aco-pending patent application entitled “ADAPTER FOR WELDING OBJECTS TOPLASTIC” Ser. No. ______ filed the same day as the present application,which is herein incorporated by reference in its entirety.

[0057] Due to the formations, stresses otherwise created between thefirst or second halves 12 or 14 and the fuel system module 16 areabsorbed. For example, pressurization of the fuel tank system 10 maycause the first and second halves 12, 14 to move apart. When thisoccurs, tensile stresses that would otherwise develop between the firstor second halves 12 or 14 and the fuel system module 16 are absorbed bythe flexibility of the formations.

[0058] In another embodiment, the fuel system module 16 is not fixedlycoupled to either the first half 12 or the second half 14. Instead,geometric interferences between the contours of the first half 12, thesecond half 14 and formations in the pre-formed sheet 46 hold the fuelsystem module 16 in position. In this embodiment, the fuel system module16 is mounted in, and supported by, one of the first half 12 and thesecond half 14.

[0059]FIG. 3 is a cross-sectioned side view of another embodiment of thefuel tank system 10 depicted in an assembled state (e.g. followingsealing of the first and second halves 12,14). In the illustratedembodiment, the pre-formed sheet 46 is positioned in the second half 14and is held in place by geometric interferences. The pre-formed sheet 46includes formations conforming to the contour of the second interiorsurface 40 such that the first and second housings 50, 56 are contiguouswith the second interior surface 40.

[0060] In addition, the first and second housings 50, 56 of thisembodiment are formed to extend through the cavity and selectivelycontact the first interior surface 26. Accordingly, the formationsmaintain the position of the fuel system module 16 by engagement of thepre-formed sheet 46 with the first and second interior surfaces 26, 40.The absence of mechanical connections to the first and second halves 12,14, allows the fuel system module 16 to remain flexible and rigid.Movable and flexible to absorb built up stresses, while providingstiffness for forces, such as, for example, compressive forces acting onthe first and second halves 12, 14. In another embodiment, the geometricinterferences and coupling mechanisms of the previously discussedembodiments may be used in combination.

[0061] Referring again to FIG. 2, in yet another embodiment, the fuelsystem module 16 may include at least one weld tab 60 formed to providea coupling mechanism with the first or second interior surfaces 26 or 40(FIG. 1). The weld tabs 60 are formed from the pre-formed sheet 46 toprovide flexibility and rigidity. In this embodiment, the weld tabs 60may be oriented and positioned so as to provide flexible support as wellas rigid support. In addition, the location of other formations in thepre-formed sheet 46 in the vicinity of the weld tabs 60 may furtherdetermine the support characteristics. In one embodiment, the weld tabs60 may be welded, glued or otherwise fixedly coupled with the first orsecond interior surfaces 26 or 40. In another embodiment, sleeves formedin the first or second interior surfaces 26 or 40 may be formed toslidably accept the weld tabs 60.

[0062] As further illustrated in FIG. 2, in still other embodiments, thepreformed sheet 46 includes slots 62. The slots 62 may be formed toslidably engage fingers extending from the first or second interiorsurfaces 26 or 40. The design and position of the slots 62 within thepre-formed sheet 46 provides a predetermined range of motion of the fuelsystem module 16.

[0063]FIG. 4 is a perspective view of another embodiment of the fueltank system 10 with portions cutaway to illustrate an embodiment of thefuel system module 16 included therein. The fuel tank system 10 alsoincludes a first half 12, a second half 14, an access port 28, a fillneck 30, a cap 32 and a plurality of fuel system components 44 similarto the previously described embodiments. In addition, the fuel systemmodule 16 includes the pre-formed sheet 46 and at least one fuel systemcomponent 44.

[0064] In the illustrated embodiment, the fuel system module 16 iscoupled to the first interior surface 26 of the first half 12. As in theprevious embodiments, the pre-formed sheet 46 is a predetermined shapeproviding a continuous layer between the first half 12 and the secondhalf 14. In addition, the pre-formed sheet 46 is formed to providerigid, yet flexible, structural support for the fuel system components44.

[0065] The fuel system components 44 positioned on the pre-formed sheet46 are a first rollover valve 44 d, a second rollover valve 44 e and aninterconnecting hose 44 f. The first and second rollover valves 44 d and44 e are positioned away from each other in a predetermined position bythe preformed sheet 46. In this embodiment, the remaining fuel systemcomponents 44 are installed away from the fuel system module 16. Inother embodiments, however, the pre-formed sheet 44 may be enlarged toaccommodate positioning of additional fuel system components 44 andadditional functionality on the fuel system module 16.

[0066]FIG. 5 is a top view of the fuel system module 16 illustrated inFIG. 4 that has been removed from the fuel tank system 10. In addition,the fuel system components 44 d, 44 e and 44 f have been removed. Thepre-formed sheet 46 is shaped in a longitudinally extending channel witha first end 62 and a second end 64. The channel includes a base 66 withwalls 68 extending perpendicularly from the base 62. Near the first end62 is a first aperture 70 formed to accommodate the first rollover valve44 d, and a second aperture 72 formed near the second end 64 toaccommodate the second rollover valve 44 e. The first and secondapertures 70, 72 represent a screw connection, a snap fit connection, afriction fit connection or any other form of mechanical connection withthe first and second rollover valves 44 d, 44 e. In other embodiments,the first and second rollover valves 44 d, 44 e may be coupled with thepre-formed sheet 46 by welding, gluing or any other mechanism thatprovides coupling.

[0067] The base 66 in cooperative operation with the walls 68 providesrouting and support for the interconnecting hose 44 f as bestillustrated in FIG. 4. In TO other embodiments, routing for additionalfuel system components 44 may also be provided. Referring now to FIGS. 4and 5, the base 66 and the walls 68 provide rigidity of the pre-formedsheet 46 to maintain the first and second roll over valves 44 d, 44 eadjacent to the first interior surface 26. The base 66 and the walls 68also provide flexibility in allowing the first and second ends 62, 64 tomove closer together and further away. The first and second ends 62, 64may move as a result of compressive and tensile forces actingsubstantially parallel to surfaces of the fuel system module 16.

[0068] The fuel system module 16 may be fixedly coupled to the interiorsurface 26 of the first half 12. Although not illustrated, as inpreviously discussed embodiments, the preformed sheet 46 may includeformations such as, weld tabs 60, slots 62, arid/or areas of thepre-formed sheet 46 that may be coupled with the interior surface 26.Stresses that would otherwise occur during differential shrinkage andswelling of the interior surface 26 with respect to the pre-formed sheet46 may be absorbed by the flexibility of the pre-formed sheet 46.

[0069]FIG. 6 is a perspective view of another embodiment of the fueltank system 10 with a portion cut away to illustrate another embodimentof the fuel system module 16. Similar to the previously describedembodiments, the fuel tank system 10 of this embodiment also includes afirst half 12, a second half 14, an access port 28, a fill neck 30 and acap 32. In addition, the fuel system module 16 includes the pre-formedsheet 46 and fuel system components 44 that include the FLW 44 a and avapor removal hose 44 g.

[0070] In the illustrated embodiment, the fill neck 30 is a conduitextending a predetermined distance into the chamber formed by the firstand second halves 12, 14. In addition, a reservoir 80 is formed in theinterior surface 40 of the second half 14. The fuel system module 16includes formations to allow mounting within the second half 14 by oneof the previously discussed techniques.

[0071] In this embodiment, the pre-formed sheet 46 is functionallyformed to support and route the fill neck 30 as illustrated. Further,the pre-formed sheet 46 includes formations to provide a channel 82 todirect liquid flowing from the fill neck 30 to the reservoir 80. Theformations within the pre-formed sheet 46 supporting the fill neck 30and forming the channel 82 provide rigidity to maintain the flow ofliquid into the reservoir 80. In addition, flexibility is also includedto absorb the stresses caused by high velocity liquid flowing out of thefill neck 30.

[0072] The pre-formed sheet 46 is also functionally formed to rigidlymaintain the position of the FLW 44 a, provide routing for the vaporremoval hose 44 g and provide rigid structural support between the firsthalf 12 and the second half 14. The structural support is provided by aseries of ridges 84 that are formed to extend from the second interiorsurface 40 to contact the first interior surface 26 of the first half12.

[0073] Referring now to FIGS. 1-6, the previously discussed embodimentsof the fuel tank system 10 utilize the fuel system module 16 to providea flexible, yet rigid, low permeation fuel tank with internalized fuelsystem components. Low permeation is achieved by inserting the fuelsystem module 16 within the fuel tank system 10 during manufacturingwithout compromising the hydrocarbon barrier. Flexibile as well as rigidsupport for the fuel system components 44 and the fuel tank system 10 isprovided by the pre-formed sheet 46 included in the fuel system module16.

[0074] The pre-formed sheet 46 is a continuous layer formed in apredetermined shape to provide functionality as well as address stressesdeveloped in the fuel tank system 10. Formations included in thepre-formed sheet 46 provide for positioning of fuel system components 44as well as the ability to provide suitable compressive resistance topromote proper internal welding of fuel system components 44 to thefirst and second interior surfaces 26, 40. In addition, formations mayact as stiffners to resist tank collapse under vacuum and/orundesireable bending or warping. Futher, the formations may be shaped tochannel fuel, provide a reservoir for fuel, act as a baffle for sloshabatement and provide routing for the fuel system components 44.

[0075] Due to the thin wall properties of the pre-formed sheet 46, fuelcapacity within the fuel tank system 10 is maximized. In addition,inherent adaptibility in designing the formations in the pre-formedsheet 46 allows the adaptation of the fuel system module 16 to thecontours of almost any fuel tank design. Finally, selection of thetechnique and locations for fixedly positioning the fuel system module16 within the fuel tank system 10 provides efficient and economicalmanufacturing while maximizing functionality and structural support.

[0076] While the invention has been described above by reference tovarious embodiments, it will be understood that many changes andmodifications can be made without departing from the scope of theinvention. It is therefore intended that the foregoing detaileddescription be understood as an illustration of the presently preferredembodiments of the invention, and not as a definition of the invention.It is only the following claims, including all equivalents that areintended to define the scope of this invention.

What is claimed is:
 1. A container comprising: a first half of the container; a second half of the container coupled with the first half to define a chamber; and a pre-formed sheet coupled with one of the first half and the second half, the pre-formed sheet positioned within the chamber to provide flexible and rigid structural support to the container.
 2. The container of claim 1, wherein the pre-formed sheet is operable to exhibit rigidity to forces imparted substantially perpendicular to the preformed sheet.
 3. The container of claim 1, wherein the pre-formed sheet is operable to exhibit flexibility to forces imparted substantially parallel to the preformed sheet.
 4. The container of claim 1, wherein the preformed sheet comprises a fluid reservoir.
 5. The container of claim 1, wherein the pre-formed sheet is operable to channel fluid within the chamber to a reservoir.
 6. The container of claim 1, wherein each of the first half and the second half are formed from thermoplastic sheets.
 7. The container of claim 1, wherein the first half and the second half operably cooperate to form a barrier surrounding the chamber, the barrier operable to limit migration of fluid from the chamber.
 8. The container of claim 1, wherein the container comprises a low permeation plastic fuel tank.
 9. A low permeation fuel tank comprising: a fuel system module comprising a continuous pre-formed sheet; and a first half and a second half of the low permeation fuel tank positioned to surround the fuel system module, the fuel system module formed to the contours of at least one of the first half and the second half.
 10. The low permeation fuel tank of claim 9, wherein the fuel system module is operable to resist movement of the first half toward the second half.
 11. The low permeation fuel tank of claim 9, wherein the fuel system module is operable to flexibly move in response to expansion of one of the first half and the second half.
 12. The low permeation fuel tank of claim 9, wherein the continuous preformed sheet comprises a formation with provisions to couple with one of the first half and the second half.
 13. The low permeation fuel tank of claim 12, wherein the formation comprises at least one of a weld tab, a slot and an area of the continuous preformed sheet contiguous with one of the first half and the second half.
 14. The low permeation fuel tank of claim 9, wherein the fuel system module comprises thermoplastic.
 15. The low permeation fuel tank of claim 9, wherein the first half and the second half comprise multiple layer thermoplastic sheets.
 16. The low permeation fuel tank of claim 9, wherein the fuel system module comprises a fuel system component.
 17. The low permeation fuel tank of claim 16, wherein the fuel system module is operable to temporarily maintain the fuel system component in position to weld to one of the first half and the second half.
 18. The low permeation fuel tank of claim 9, wherein the fuel system module is operable to channel fuel to a fuel reservoir within the low permeation fuel tank.
 19. A low hydrocarbon emission fuel tank comprising: a first thermoplastic sheet and a second thermoplastic sheet each comprising a plurality of layers; a weld joint operable to couple the first thermoplastic sheet and the second thermoplastic sheet to form the fuel tank, the first and second thermoplastic sheets operable to provide a hydrocarbon barrier; and a fuel system module positionable within the fuel tank prior to application of the weld joint to minimize discontinuities in the hydrocarbon barrier, the fuel system module comprising a pre-formed sheet and a fuel system component.
 20. The low hydrocarbon emission fuel tank of claim 19, wherein the preformed sheet comprises a continuous sheet in a predetermined functional shape the pre-formed sheet forming a layer between the first thermoplastic sheet and the second thermoplastic sheet.
 21. The low hydrocarbon emission fuel tank of claim 19, wherein the fuel system module is coupled to the first thermoplastic sheet.
 22. The low hydrocarbon emission fuel tank of claim 19, wherein the fuel system module is coupled to the second thermoplastic sheet.
 23. The low hydrocarbon emission fuel tank of claim 19, wherein the fuel system module is held in position by geometric interference between formations in the pre-formed sheet and contours of the first thermoplastic sheet and the second thermoplastic sheet.
 24. The low hydrocarbon emission fuel tank of claim 19, wherein the fuel system module is formed to position one of at least two fuel system components away from another of the at least two fuel system components.
 25. The low hydrocarbon emission fuel tank of claim 19, wherein the fuel system module comprises a first end and a second end, one of at least two fuel system components positioned near the first end and another of the at least two fuel system components positioned near the second end.
 26. The low hydrocarbon emission fuel tank of claim 19, wherein the preformed sheet comprises formations, the formations with provisions to couple the fuel system module with one of the first thermoplastic sheet and the second thermoplastic sheet.
 27. The low hydrocarbon emission fuel tank of claim 26, wherein the formations are operable to allow flexible movement of the fuel system module in response to forces acting substantially parallel to surfaces of the preformed sheet.
 28. The low hydrocarbon emission fuel tank of claim 26, wherein the formations are operable to resist movement of the fuel system module in response to forces acting substantially perpendicular to surfaces of the preformed sheet.
 29. A fuel system module for installation in a low hydrocarbon emission fuel tank, the fuel system module comprising: a pre-formed sheet; the pre-formed sheet with provisions to support a fuel system component in a predetermined position; and the pre-formed sheet formed to fit within the low hydrocarbon emission fuel tank with provisions to couple with an interior surface of the low hydrocarbon emission fuel tank.
 30. The fuel system module of claim 29, wherein the pre-formed sheet is operable to flexibly absorb forces applied substantially parallel to surfaces of the pre-formed sheet and rigidly withstand forces applied substantially perpendicular to surfaces of the pre-formed sheet.
 31. The fuel system module of claim 29, wherein the pre-formed sheet is contiguous with the contours of the interior surface.
 32. The fuel system module of claim 29, wherein the pre-formed sheet comprises thermoplastic.
 33. The fuel system module of claim 29, wherein the pre-formed sheet comprises functional features of the low hydrocarbon emission fuel tank.
 34. The fuel system module of claim 29, wherein the pre-formed sheet is operable as a structural support.
 35. A method of internalizing fuel system components, the method comprising: forming a first half of a fuel tank; forming a second half of the fuel tank; mounting a fuel system module in one of the first half and the second half of the fuel tank, the fuel system module comprising a pre-formed sheet and a fuel system component; and joining the first half and the second half to surround the fuel system module and form the fuel tank, wherein the fuel system module forms a continuous layer between the first half and the second half.
 36. The method of claim 35, further comprising coupling the fuel system module to an interior surface of one of the first half and the second half.
 37. The method of claim 35, further comprising positioning the fuel system module within a concave shape formed in one of the first half and the second half.
 38. The method of claim 35, further comprising preserving a hydrocarbon barrier provided by the first half and the second half during mounting of the fuel system module.
 39. The method of claim 35, further comprising applying pressure to the fuel system module to couple the fuel system module to one of the first half and the second half.
 40. The method of claim 35, further comprising forming the fuel system module in a predetermined shape contiguous with the contours of at least one of the first half and the second half.
 41. A method of creating a fuel system module for internalizing fuel system components, the method comprising: forming a sheet in a predetermined shape; creating provisions on the sheet to fixedly couple the sheet to an internal surface of a fuel tank; and positioning a fuel system component on the sheet.
 42. The method of claim 41, further comprising routing the fuel system component with the sheet.
 43. The method of claim 41, wherein forming the sheet comprises forming a fuel reservoir as part of the sheet.
 44. The method of claim 41, further comprising testing to verify cooperative operation of the fuel system component and the sheet.
 45. The method of claim 41, wherein the sheet comprises thermoplastic and configuring the sheet comprises molding the sheet to the predetermined shape.
 46. The method of claim 41, wherein forming the sheet comprises shaping formations in the sheet to provide rigidity to forces applied substantially perpendicular to a surface of the sheet and flexibility to forces applied substantially parallel to a surface of the sheet.
 47. The method of claim 41, further comprising installing the sheet in a fuel tank. 